I’m not sure it’s correct for members to be deciding whether a minhag sounds good to them, or makes sense to them, or is logical, or seems illogical etc. A minhag was definitely established not to learn Torah on certain nights that coincide with non-Jewish events. Whether or not we understand that, or approve of it, is not for us to decide. You probably already know whether your kehilla observes this minhag or not. If you’re in Yeshiva, or attend a shiur, your Rosh Yeshiva or Rav has decided for you. (In the case of this particular minhag it seems clear that there’s a reason it was often not recorded in written responsa.)
I find it similarly inane when Pesach comes and people put forth vapid arguments on why refraining from eating gebrochtz is or is not a sensible minhag. It’s really not for us to decide how much sense it makes. And if we were privileged to sit at the seder with our parents (or husbands, if we’re married ladies) then we already know what we have to do.
I’m just wondering if anyone knows the source for the fact that the Hebrew date for the birth of this person who brought such darkness to the world is 9 Teves, one day before the fast of Asara B’Teves.